CN O-18-a

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CN O-18-a
Type and origin
Power type Steam
Builder Grand Trunk Railway's Point St. Charles Shops
Build date 1919-1921
Total produced 50
 • Whyte 0-6-0
 • UIC C
Gauge 4 ft 8 12 in (1,435 mm)
Driver dia. 51 in (1.295 m)
Loco weight 174,000 lb (78.9 tonnes)
Fuel type Coal
Boiler pressure 175 lbf/in2 (1.21 MPa)
Cylinders Two, outside
Cylinder size 22 in × 26 in (559 mm × 660 mm)
Performance figures
Tractive effort 36,703 lbf (163.26 kN)
Operators Grand Trunk Railway » Canadian National Railways
Class GTR: F9
CN: O-18-a
Numbers GTR: 1749–1798,
CN: 7424–7473
Scrapped 1954–1961
External images
Locomotive 7456 on display at Montcalm Community College
7439 at work in Chatham, Ontario
7470, the only operable O-18a locomotive today

CN O-18-a is a class of 0-6-0 steam locomotives formerly owned by Canadian National Railways. They were switchers built by the Grand Trunk Railway's Point St. Charles Shops. Canadian National used the letter O to designate 0-6-0s.

The Grand Trunk Railway built 50 of these locomotives between 1919 and 1921 and designated them F9 Class. The GTR also had 25 more built in 1920 by the Lima Locomotive Works for use in the United States. In 1923, the Grand Trunk Railway was absorbed by the Canadian National Railways. CN classified the homebuilt locomotives O-18-a and the Lima-built F9s became GTW O-18-b class.

The O-18-a locomotives were numbered 1749–1798 by the Grand Trunk, and were renumbered as 7423–7473 by the Canadian National. They operated right up until dieselisation.

Upon retirement, 47 of the 50 locomotives were scrapped, but three were sold. CN 7439 (GTR 1764) was sold to International Harvester in 1958, but was scrapped only three years later in 1961. Canadian National 7456 (GTR 1781) and Canadian National 7470 (GTR 1795) were sold to Canada and Dominion Sugar (Chatham, Ontario) in 1959. Two survive to the present. (7470, and 7456)

O-18-a number 7456 is at Montcalm Community College as a display locomotive, while number 7470 resides at the Conway Scenic Railroad in North Conway, New Hampshire and is currently nonoperational due to its federally mandated inspection for the next two years.


  • Edson, William D.; Corley, Raymond F. (Autumn 1982). "Locomotives of the Grand Trunk Railway". Railroad History. The Railway and Locomotive Historical Society, Inc. (147): 142.